So I was crunching the numbers and, it seems that cybernetic surgery is very difficult to successfully complete. Even with 5 in medical, having 5 droids with 3 in medical skill each, doing the easiest cybernetic installation possible, and performing the surgery on Coruscant (66.800% civilization level) the formula looks like this:

The 'bad happened' is only a 10 % chance after the initial fail, which is why I think it really ought to be a low success rate off the bat - in or around 50 % seems about right to me since it's ultimately way overpowered if you successfully implant a vast majority of the time.

For cases where the chance of success are 56 %, you really only have a 4.4 % chance of ending up with a faulty cybernetic, so that's still pretty rare.

Excellent. One last question on this thread pertaining to civilization levels.

How do I measure the civilization level of a space station? The rules state that a cybernetic implant may be installed in a medical faction owned hospital station. How do I calculate the success formula if an operation were to be conducted in outer space?